
In The Beginning...
Rudimentary
elevators, or hoists, were in use during the Middle Ages and
can be traced back to the third century BC. They were operated
by animal and human power or by water-driven mechanisms. The
elevator as we know it today was first developed during the
1800s and relied on steam or hydraulic plungers for lifting
capability. In the latter application, the cab was affixed
to a hollow plunger that lowered into an underground cylinder.
Liquid, most commonly water, was injected into the cylinder
to create pressure and make the plunger elevate the cab, which
would simply lower by gravity as the water was removed.
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Valves
governing the water flow were manipulated
by passengers using ropes running through the cab, a system
later enhanced with the incorporation of lever controls and
pilot valves to regulate cab speed. The "granddaddy" of
today's traction elevators first appeared during the 19th
century in the U.K., a "lift" using a rope running
through a pulley and a counterweight tracking along the shaft
wall.
Give Us the Power...
The power
elevator debuted mid-19th century in the U.S. as a simple freight
hoist operating between just two floors in a New York City
building. By 1853, Elisha Graves Otis was at the New York Crystal
Palace exposition, demonstrating an elevator with a "safety" to
break the cab's fall in case of rope failure, a defining moment
in elevator development.
By
1857, the country's first Otis passenger elevator was in operation
at a New York City department store, and, ten years later,
Elisha's sons went on to found Otis Brothers and Company in
Yonkers, NY, eventually to achieve mass production of elevators
in the thousands. Various other elevator designs appeared on
the landscape, including screw-driven and rope-geared, hydraulic
models.
An Electric Moment...
Later in
the 1800s, with the advent of electricity, the electric motor
was integrated into elevator technology by German inventor
Werner von Siemens. With the motor mounted at the bottom of
the cab, this design employed a gearing scheme to climb shaft
walls fitted with racks. In 1887, an electric elevator was
developed in Baltimore, using a revolving drum to wind the
hoisting rope, but these drums could not practically be made
large enough to store the long hoisting ropes that would be
required by skyscrapers.
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Motor technology
and control methods evolved rapidly. In
1889 came the direct-connected geared electric elevator, allowing
for the building of significantly taller structures. By 1903,
this design had evolved into the gearless traction electric
elevator, allowing hundred-plus story buildings to become possible
and forever changing the urban landscape. Multi-speed motors
replaced the original single-speed models to help with landing-leveling
and smoother overall operation. Electromagnet technology replaced
manual rope-driven switching and braking. Push-button controls
and various complex signal systems modernized the elevator
even further. Safety improvements have been continual, including
a notable development by Charles Otis, son of original "safety" inventor
Elisha, that engaged the "safety" at any excessive
speed, even if the hoisting rope remained intact.
As Good As It Gets...
Today, there
are intricate governors and switching schemes to carefully
control cab speeds in any situation. "Buttons" have
been giving way to keypads. Virtually all commercial elevators
operate automatically and the computer age has brought the
microchip-based capability to operate vast banks of elevators
with precise scheduling, maximized efficiency and extreme safety.
Elevators have become a medium of architectural expression
as compelling as the buildings in which they're installed,
and new technologies and designs regularly allow the human
spirit to soar!
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